1. Field of the Invention
The present invention relates to a transmission control apparatus.
2. Discussion of the Background
There are transmission control devices for automatic transmissions that automatically or semi-automatically select the most suitable shift position on the basis of information on the vehicle speed, the engine speed, the throttle opening, and the like. For such transmission control devices, a configuration has heretofore been known in which under a given circumstance, the gear-shift condition is made different from that in a normal running state.
Japanese Patent Application Publication No. 2007-218269 discloses a transmission control device for an automatic transmission used in a motorcycle. Specifically, the transmission control device obtains the lateral lean angle (bank angle) of the vehicle body through detection with a lean angle sensor or through calculation of the vehicle speed and the steering angle. Then, while the lean angle is above a predetermined value, the transmission control device assumes that the motorcycle is turning (in cornering state), and performs no gear-shift control even if a gear shift condition is met.
However, the technique described in Japanese Patent Application Publication No. 2007-218269 is one that simply inhibits gear shift operation while the bank angle of the vehicle body is above a predetermine value, and does not take into consideration the performing of gear-shift control according to various cornering states that differ from one another in vehicle speed, bank angle, and the like. In conventional practices, an expensive sensor such as a bank angle sensor or a gyroscope is needed to determine the cornering state. However, use of such a sensor in a motorcycle is sometimes difficult. Thus, it has been desired to determine the cornering state with an inexpensive system using no expensive sensor.